Technical Field
The present invention relates to a rotor applied to an extractor-fan assembly for agricultural machines, especially for sugar-cane harvesters, the rotor comprising a set of blades fixed to a hub, defining medium and trailing root angles, which facilitate displacement of air along the blades.
Description of Related Art
The extractor-fan assembly used on agricultural machines and more specifically on sugar-cane harvesters comprises a metallic cap which houses a rotor, a central axle, a hub and a set of blades.
The extractor-fan assembly is responsible for cleaning the harvested material, separating trash and earth from sugar-cane billets and also responsible for distributing the trash and earth over the ground surface.
The set of blades of the extractor-fan assembly is responsible for displacing the air flow that carries impurities, by turning the rotor. The displacement of air flow results in higher or lower efficacy of the extractor-fan assembly.
Constructions for the blades of the extractor-fan assembly used on sugar-cane harvesters are known from the prior art, as for example, the construction described in U.S. Pat. No. 4,155,602, which relates to a blade of an extractor-fan assembly having three straight profiles comprising a central portion, a leading portion and a trailing portion. These straight profiles cause greater turbulence in the air.
U.S. Pat. No. 6,869,356 and PI1104385-7 describe blades applied to extractor fans with two straight profiles, either folded or inclined to each other, one profile being intended for exit of air and the other profile being integral with the blade body.
Further, as a prior-art document, one can cite PI0302278-1, which describes a blade with a profile grooved in only one direction. This grooved profile, in spite of providing good displacement of air, is deficient in both entry of air, due to the lack of trailing angle, and ion exit of air due to the lack of trailing angle.
The need for high power for driving the extractor-fan assembly due to its inefficiency, as can be observed on conventional harvesters, implies directly greater consumption of fuel (diesel), higher operational cost and greater environmental impact due to larger emission of gases by harvester engines.
Moreover, studies carried out by Churchward and Belcher (1972), entitled: “Some economic aspects of mechanical cane harvesting in Queensland, Proc. Qd Soc. Sugar Cane Technol. 39th Conf. 31-38”, showed that each extractor-fan assembly of prior-art sugar-cane harvesters consume about 60 HP for efficiently cleaning the harvested cane. It should be reminded that the great majority of harvesters use two extractor-fan assemblies, the consumed power corresponding to 120 HP.
The new configuration proposed in this specification, enables the harvesters to carry out their work with only one extractor-fan assembly per machine, generating a consumption of 30 HP, saving diesel and consequently reducing the harvesting operation cost.